I'd probably pick the torture, too, but I think proponents of humane killing are comparing it with inhumane killing, so it's more like, would you rather choose

I'd probably pick the torture, too, but I think proponents of humane killing are comparing it with inhumane killing, so it's more like, would you rather choose to die painlessly, or endure weeks of incredibly painful torture before being killed. I'd probably choose the former in that case.